//
//  main.cpp
//  P1423
//
//  Created by 洋犀利 on 2019/8/29.
//  Copyright © 2019 洋犀利. All rights reserved.
//
//小玉swimming

#include <iostream>
using namespace std;

int main(int argc, const char * argv[]){
    double total = 0.0000;
    double x = 0.0000;
    double now = 2.0000;
    cin>>x;
    int i=0;
    for(;x>=total;i++){
        total = total +now;
        now = 0.98*now;
    };
    cout<<i;
    return 0;
}
